1. Field of the Invention
The present invention relates to glass transmissivity and particularly to fiber optic cables having reduced transmission loss.
2. Related Art
Fiber optic cable is a well known media for transmission of an optical signal from a source of the optical signal to a receiver for that signal. One of the most important applications of fiber optic technology is in the long-haul transmission of communications signals, where an electrical (usually digital) signal from a communications signal source (e.g., telephone or data modem) is modulated onto a light wave and transported via a fiber optic connection to a receiver (where the electrical signal is recovered through a demodulation process).
A critical factor in communications applications of fiber optic technology is the attenuation or loss characteristic of the fiber optic cable used as the transmission medium. As is well known, signals transmitted via a fiber optic channel are attenuated as they travel along the channel, and at some distance from the signal source reach a sufficiently low level as to require amplification by a “repeater” inserted in the fiber channel at that point. Thus, the loss characteristic of the fiber optic cable is directly related to the distance between repeaters for the fiber optic channel.
It is generally desirable to minimize the number of repeaters in a fiber optic channel and correspondingly to maximize the length of the sections of fiber optic cable between each set of repeaters. To that end, the attenuation or loss characteristic of the fiber optic cable for a desired band of optical signals is also desirably minimized.
The technology of the current art for fabrication of fiber optic cable is based on germanium (Ge) doped silica (Si). The losses in current-technology fiber optic cables are on the order of 0.16 db/kilometer, which is essentially the theoretical maximum transparency of silica. Thus it would be advantageous to produce a lower loss fiber which would permit longer fiber links between repeaters.